About

Hagfish versus sharks : 1-0

Not many of you will believe that hagfish, also called snot-eels, are fascinating creatures, but they truly are. You will only be able to believe me after reading this post. I still persist saying that I am not falling in love with them but some of my colleagues start worrying about my desire to always know more on their behaviour. Another step in this direction, I just published with colleagues from Te Papa, Massey University and the University of Western Australia a paper describing new extraordinary behaviours of my current favourites.

Hagfish teeth. Hagfish are equipped with four rows of keratinous teeth that they can use to grasp and bite flesh from dead animals or live prey.

Hagfish are deep-sea primitive fishes which have been living on Earth for at least 300 millions years, almost unchanged. They are like living fossils and scientists wonder how it is possible that they could survive for such a long time on Earth. To give you an idea of how long 300 millions years is, keep in mind that the dinosaurs appeared on Earth about 230 millions years and went extinct about 65 millions ago. With this research, we reveal a few more clues on what make hagfishes so special.

Hagfish were thought to fulfil primarily the ecological niche of scavengers in the deep ocean, i.e. we thought they were feeding on dead animals only. Reviewing video footage taken in New Zealand waters, we now know that they are also able to hunt for live preys such as fishes. During a video deployment off Great Barrier Island at 97 m depth, one hagfish species was successfully observed predating on a red bandfish.

But there is more. After carefully reviewing over 1000 hours of underwater video footage, I realized that not a single shark or other large fish could bite and feed on hagfish. Hagfish versus sharks and co: 1-0! What happens is that every time a large fish tries to attack, the hagfish produce large amount of slime at incredible speed. This slime then clogs the gills of those would-be predators which start choking, unable to breathe. Amazingly, not a single attack resulted in successful predation! This is an extremely effective defence mechanism, totally unique.

The paper describing those two newly observed behaviours can be downloaded here from the journal Scientific Reports.